<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <script src="./js/jquery-3.6.0.js"></script>
  </head>
  <body>
    <input type="text" id="name" />
  </body>
</html>
<script>
  $('#name').keydown(function () {
    //二选一
    $(this).css('background-color', 'red')
    $("#name").css('background-color', 'red')
  })

  $('#name').keyup(function () {
    $(this).css('background-color', 'white')
    $('#name').css('background-color', 'white')
  })
</script>
